SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1122 AM CDT Fri Mar 28 2025 Valid 281630Z - 291200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF COASTAL TEXAS INTO LOUISIANA AND PORTIONS OF NEBRASKA INTO THE UPPER MIDWEST... ...SUMMARY... A low probability tornado/wind threat is forecast through this evening across parts of coastal Texas into Louisiana. Isolated severe hail and wind is also possible this evening/tonight from Nebraska into portions of the Upper Midwest. ...Coastal Texas into Louisiana... Satellite imagery late this morning shows a mid-level trough over south-central TX into northeastern Mexico, and a vorticity max over the middle coastal plain of TX. Largely displaced from incipient outflow-generated air from a couple of western Gulf thunderstorm clusters, southeasterly low-level flow is advecting richer moisture into southeast TX/western LA. Cloud breaks will lead to some heating from the middle to upper coasts of TX into western LA. Surface dewpoints ranging from the upper 60s near the coast to the mid 60s as far north as I-20, will contribute to 250-1000 J/kg MLCAPE per model forecast soundings. Sufficiently enlarged low-level hodographs (0-1 km SRH 100-200 m2/s2) and a moist boundary layer and appreciable 0-3km CAPE, will support a conditional setup for several mini supercells. The main threats with this highly dependent mesoscale scenario would be a risk for a couple of tornadoes and localized damaging gusts. Uncertainty is rather high regarding this forecast due to low confidence in a few warm sector cells developing this afternoon. However, if isolated to scattered storms were to develop, the greatest potential severe threat would occur primarily in the 18-00 UTC period. This potential activity would likely diminish by early to mid evening owing to the loss of daytime heating. ...Nebraska into the Upper Midwest... Upper ridging will be gradually suppressed today as a low-amplitude shortwave trough moves eastward across the northern/central Plains and Upper Midwest through the period. Modest low-level moisture is forecast to continue streaming northward along/south of a sharpening warm front across MN/WI, and east of a cold front that will develop southward across parts of the northern/central Plains by this evening. Isolated to scattered thunderstorms may develop by mid to late evening along/near both fronts as low-level warm advection strengthens, from central NE northeastward into southern MN and central WI. Steep mid-level lapse rates will aid in the development of moderate MUCAPE, while deep-layer shear appears marginally supportive of organized convection. Any sustained thunderstorms could produce isolated severe hail and damaging winds. This activity will likely be elevated with eastward extent into the Upper Midwest through the evening and overnight, with a continued hail threat. ..Smith/Moore.. 03/28/2025